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Replacing old broken steam boiler

Mitch_6 Member Posts: 549
you may want to change over to forced hot water. Install baseboard radiation or hydro air. Maybe some radiant and an indirect water heater. FHW boilers allow for a lot of flexibility and zoning can increase comfort and reduce operating cost.

Up front cost is an issue a boiler swap could be 4 to 6k a total refit to FHW could be three times that and up. Oil or gas is personal preference pro's & con's on both sides, I am more on the side of gas, feel it is cleaner and easier to work with.

You will get out of your system what you put into it.

Also never use copper above the water line. I have seen two pipe steam converted to FHW. Not usually single pipe. The radiators need to be nippled across the top and changing from 1 to 3 psi steam to 12 to 21psi water may develop some leaks and bring allot of sludge into a new boiler if you do not prep it right.

Mitch S.


  • Rich Solomon
    Rich Solomon Member Posts: 1

    I have an old oil fired steam boiler that developed leaks both above and below the water line. I am considering replacing it with a natural gas fired boiler. I also want to relocate a section of the cast iron main that is inconviently located right in the center of the basement. One contractor suggested replacing a section of the cast iron steam main with copper. Another contractor was emphatic about only using cast iron and not copper. Any thoughts either way?

    I has also been suggested that I may want to consider changing over to a hot water system on the theory that since you only have to heat the water to 180 deg instead of 212 deg, hot water is much more efficient than steam. Is this true and if so, can I still use the existing single pipe steam radiators in a hot water system?
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    Before you do anything

    compare the cost-per-BTU of oil vs. gas in your area. Be sure to include all taxes and fees- these are usually already figured into the oil price (140,000 BTU per gallon) but not into gas (100,000 BTU per therm, 900-1150 BTU per cubic foot depending on how they bill). You might be surprised to see how much more expensive gas has become, compared to oil.

    I wouldn't try to convert that system to hot-water. Assuming similar boilers and that both systems are in good condition, the difference in total system efficiency isn't much, and the cost is high enough to preclude a good ROI especially if something goes wrong. Also there are too many pitfalls, not the least of which is the probability of leakage. The guy who suggested that doesn't understand steam. Go here for more:


    Never use copper on steam pipes. Whoever suggested that doesn't know steam. The soldered joints can break. Black pipe only. For "wet" return lines that are always full of water, copper is OK.

    Try the Find a professional page of this site to locate a steam man near you. If you're in the Baltimore area, contact me.


    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
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